"Students, this class is about the basics of mechanical manufacturing. Who can tell me what is the definition of mechanical manufacturing?" In the classroom of the Department of Mechanical Engineering, the words from Professor Zhuang Qianding, the head of the department, echoed around. He stood
On the podium, I opened the pure English version of the foreign "Mechanical Engineering" textbook and asked the whole class.
There are about twenty students in the classroom, basically all first-year students from the Department of Mechanical Engineering, and a small number of elective students from the Department of Civil Engineering.
Yu Hua is the only mathematics student among the group of students.
As one of the few top mechanical experts in Tsinghua University, Professor Zhuang Qianding is extremely talented and outstanding. His personal experience is just like that of Professor Zhao. After returning from studying abroad, he personally established the Department of Mechanical Engineering at Tsinghua University.
Bachelor's degree from Nanyang Public School, a master's degree in mechanical engineering from Cornell University, a member of the American Scientific Research Honor Society, a master's degree in chemical engineering, and served as an engineer at Boston Sway Engineering Company and a test engineer at the Detroit Edison Company power plant.
This is Professor Zhuang Qianding’s academic qualifications and resume. He is one of the few in the country who has high attainments in the field of mechanical engineering.
Yu Hua sat quietly at the back of the classroom, systematically learning knowledge in the field of mechanical engineering. Most of his understanding of mechanical manufacturing came from television. The knowledge points were extremely basic and one-sided. Only through systematic learning can he improve himself from a fundamental level.
With the addition of Professor Zhuang Qianding, the level of the Department of Mechanical Engineering at Tsinghua University is no less than that of Nanyang Public School, an old and prestigious school.
"The process of producing mechanical parts and assembling them into machines, instruments or equipment is called mechanical manufacturing." A boy wearing glasses stood up immediately.
"It seems that this classmate has already previewed it. Yes, this is the definition of machinery manufacturing. The machinery manufacturing industry serves all the needs of people's lives. It is one of the most important industrial categories in the complete industrial system, comparable to the metallurgical industry.
.”
Professor Zhuang Qianding nodded with satisfaction, motioned the student to sit down, and looked around the crowd: "Processing metal materials into mechanical parts is the main link in mechanical manufacturing. Its processing methods are usually divided into three categories, namely hot processing, cold processing and special processing.
Processing, can any classmate please tell me what the method of thermal processing is?"
"There are three methods of thermal processing, casting, forging, and welding." Immediately afterwards, another slightly thin classmate wearing glasses stood up and explained the three methods of thermal processing in detail.
"Casting, forging, and welding, each of these three methods has its own advantages and disadvantages. The advantage of casting is that it can manufacture parts with very complex geometric shapes. The shape and size are usually close to the parts. It has a wide range of adaptability, a wide range of material sources, simple process equipment, and low production costs.
Low."
Zhuang Qianding nodded and pressed his hand to the classmate: "The disadvantages are that there are many production processes, the process is difficult to control, the quality is not stable enough, the scrap rate is high, and shrinkage cavities, looseness, cracks, gaps, and pores are prone to occur internally.
There are defects such as blisters, and the performance of castings is not as good as that of forgings. Can any student tell me about the advantages and disadvantages of forging?"
Zhuang Qianding’s lectures attach great importance to interaction with students because this can improve the quality of lectures.
If the teacher just writes on the blackboard and speaks on the podium, the students below will be confused, the quality of the lecture will be very low, and the students will not master the knowledge at all.
As soon as this question came out, the classroom became quiet.
"The main advantage of forging is to improve the internal structure of metal, eliminate internal defects such as cracks, pores and blisters, etc., and improve the mechanical properties of metal blanks. For heavy-load mechanical parts, such as heavy machine parts, spindles and connecting rods,
Gears, barrels of military weapons, and gun barrels must go through the forging process. Then, they have high production efficiency and a wide range of applications. The geometric shapes range from simple bolts and nuts to complex crankshaft connecting rods, and the mass ranges from 1 gram to 100
Large shafts for ton-level warships can be manufactured using forging methods."
Feeling the cold atmosphere in the classroom, Yu Hua stood up and carefully explained the forging concept, advantages and disadvantages he had just read in the textbook:
"The disadvantage of forging is that it is impossible to obtain parts with complex inner cavities. The material of the parts needs to have a certain degree of plasticity, which cannot be used for brittle materials such as cast iron. Moreover, the forging equipment is expensive. The price of a single air hammer may be as high as tens of thousands of yuan, and the price of a thousand-ton level
The price of a hydraulic press is as high as more than 200,000 yuan, and the first 10,000-ton hydraulic press in the United States, as shown in the textbook, costs as much as one million silver dollars."
"This classmate gave a very good answer. Classmate, what is your name?" Upon hearing Yu Hua's answer, Zhuang Qianding's eyes lit up, and he did not hesitate to praise him, and then asked.
"Hello, professor, my name is Yu Hua. I just signed up for your elective course and am a student in the Department of Mathematics." Yu Hua replied softly.
"Department of Mathematics?" The words spread throughout the classroom. Almost all the students in the Department of Mechanical Engineering present were confused and their heads were a little hard to turn.
what's going on?
People from the Department of Mathematics should take elective courses in the Department of Mechanical Engineering?
Confused, confused.
However, it was not over yet. Everyone quickly came to their senses and realized another problem - why did this person sign up for elective courses now?
General elective courses will be selected at the beginning of the semester, but the current situation is that one year of study is coming to an end and summer vacation is coming soon.
"Classmate Yu Hua, please sit down."
When Zhuang Qianding heard this, his eyes narrowed. He felt very familiar. He suddenly remembered it, smiled, motioned for Yu Hua to sit down, and then explained to other students: "Yu Hua is the top scorer in this year's joint entrance examination. Come to school early to register."
to study.”
excuse me……
Almost instantly, everyone in the classroom returned to normal, sorted out the logical sequence and reasons, and silently turned their attention to Zhuang Qianding.
You can't afford to offend someone like this who is the top scorer in the college entrance examination.
It’s not that they are cowards, after all, none of the students who can get into Tsinghua University are stupid, but they are self-aware.
"What Yu Hua just said was very good. Please take notes. In addition, let me say one more thing. In addition to hot forging, there is also cold forging. Cold forging refers to the processing of metal below the recrystallization temperature. There are model cold forgings.
And cold extrusion and other processes, currently, the cold forging process is a high-end process method, and there is no real cold forging machine in China."
Zhuang Qianding continued his lecture, turned around and wrote the English and Chinese professional terms of welding on the blackboard: "Let's talk about welding next. Welding is a process of permanently connecting metal materials. It uses heating or pressure to catch the bonding of metal atoms.
and diffusion, making the two pieces of metal materials firmly connected together..."
This section on the basics of mechanical manufacturing mainly talks about the three methods of thermal processing and their respective advantages and disadvantages, as well as the specific methods and types, from sand casting, which is subdivided from casting, to free forging and model forging in the forging field, and finally to welding.
Welding.
Fusion welding is very interesting. After Zhuang Qianding's explanation, Yu Hua now understood that the so-called arc welding, gas welding, submerged arc welding and other welding methods all belong to the characteristics of metal hot melt and are classified as fusion welding.
Professor Zhuang Qianding gave a very detailed and in-depth lecture. After explaining the basic concepts, he focused on the relevance of each process method.
Generally speaking, if you want to obtain a part with good mechanical properties, such as a gun barrel, you first need to cast the barrel blank, and then perform forging processing to improve the internal structure of the barrel blank metal and obtain finer grains, thereby
The mechanical properties are greatly improved.
In the classroom, Yu Hua and the students are like a river bed that has dried up for a long time, constantly absorbing fresh and fresh rainwater to replenish themselves.
Outside the window, the sun gradually sets, and a red halo gradually emerges from the edge of the horizon.
At 5:30, the mechanical engineering elective class ends.
"Simply assign a job to design and manufacture a part. The processing method is not limited. The shape of the part must have a certain degree of practicality. In a few lessons, we will talk about metal cutting. By then, the parts you design and manufacture will be
As a teaching aid for class, you can do it alone or as a team project."
Zhuang Qianding was meticulous and had a serious face. He stood on the podium and looked around, assigning new homework: "Okay, get out of class is over."
After finishing speaking, he turned around, walked off the podium, and walked out of the classroom.
"Thank you for your teaching." In a flash, all the students stood up, showing respect on their faces, and bid farewell to Zhuang Qianding in unison.
"Designing and manufacturing a part... is interesting." After class, Yu Hua quietly left the classroom and went to Pingzhai, the dormitory. He became interested in the homework assigned by Professor Zhuang Qianding and thought about what part to make.
"How about practicing in advance and making a gun barrel to try?"
The beauty of machinery never goes out of style. As a hardcore military fan, Yu Hua, the first 'machine' part that comes to mind is of course the most interesting gun barrel for military fans.
It is no exaggeration to call firearms a killing machine.
The soul and central foundation of the gun barrel lies in the gun barrel.
"The Department of Mechanical Engineering has a lathe and a gantry milling machine. It is no problem to make gun barrels with precision. As for rifling, I want to try the feeling of rifling by hand. That's it." Yu Hua thought about it carefully and planned to take this opportunity to try it.
Craftsmanship, no matter what parts are made, it is not made.
After making the decision happily, Yu Hua left the school and quickly returned to Pingzhai. His roommate Han Yujin was not in the dormitory and he didn't know where he was.
After changing his clothes and getting ready, Yu Hua left the dormitory and headed to the east gate of the school instead of the west gate as agreed in advance.
After coming out of Tsinghua University, Yu Hua made a habit of walking around a few times to see if anyone was following him. After confirming that there was no one following him, he immediately hailed a rickshaw on the road and headed straight to Dongcheng.
There is no rush for homework or anything like that at the moment. The most important thing at the moment is to complete the plan to replace technology with equipment!